The study analyzed text-embedded lexical usage as diagnostic of writing-speech-distinctions in stories and discussions produced in the two modalities by English-speaking grade-school children, middle-school pre-adolescents, high-school adolescents, and adults. It Assumed that (1) while children master writing as a notational system by age 9 to 10 years, command of written language as a special style of discourse has a long developmental trajectory, and (2) distinct processing constraints and communicative circumstances combine to affect texts produced in the two modalities. Across the board, written texts scored higher than their spoken counterparts produced by the same participants on all five measures that were applied — Word Length, Register, Density, Diversity, and Abstractness — reflecting a more elevated and carefully monitored style of expression. With regard to development, high school students emerged as distinct from the two younger groups, demonstrating adolescence as a developmental watershed in discourse-embedded lexical usage as in other domains of text construction. When task order (written texts produced before or after spoken ones, respectively) is taken into account, however, a more complex, multi-faceted picture emerges with respect to the variables of age, specific lexical measure, and order effects.